SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52f6d15574487f9ebb446b08e894ba67e1d9bf19ed5f1d884cd04aa0174ef17' 
  AND token = 'ZWvdXQ7MzPZiWZKYOg1hvPHZJVRz7H9AtoYgBFpQOCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}